Envelope and electrode structure for electric discharge devices



June 15, 1948. K, c, D WALT 2,443,444

ENVELOPE AND ELECTRODE STRUCTURE FOR ELECTRIC DISCHARGE DEVICES Filed July 8, 1947 Inventor:

Ken'neth C. DeWalt,

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Patented June 15, 1948 ENVELOPE AND ELECTRODE STRUCTURE FOR ELECTRIC DISCHARGE DEVICES Kenneth C. De Walt, Scotia, N. Y., assignor to General Electric Com New York pany, a corporation of Application July 8, 1947, Serial No. 759,524 v My invention relates to improved electric discharge devices and particularly to discharge devices employing a gas or vapor as an ionizable medium.

In extending the electrical rating of electrical discharge devices, particularly devices employing an ionizable medium, difficulty is encountered in adequately cooling the are stream. Various cooling structures have been supported within the enclosing envelope of devices of this type to improve the operating characteristics and to provide for devices of higher current or voltage rating. These cooling structures have not been entirely satisfactory and have often been poorly suited for economical manufacture. In accordance with an important aspect of my invention, I provide an improved gaseous electric discharge device which is readily manufactured and which, at the same time, provides for a large cooling area relative to the cross sectional area of the discharge.

It is an object of my invention to provide a new and improved electric discharge device.

It is another object of my invention to provide an improved envelope structure for an electric discharge device of the gas filled type which provides for more adequate cooling of the arc discharge.

My invention will be better understood by reference to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, the single figure is an elevational view in section of an electric discharge device embodying my invention.

In accordance with the illustrated embodiment of my invention, I provide an envelope for an electric discharge device having a large cooling area relative to the cross section of the discharge space with the additional feature that the cooling area may be increased substantially in direct proportion to the increase in the area of the discharge path as the size of the tube is increased.

Referring now to the drawing, the discharge device includes a general cylindrical envelope having an annular cross section formed by concentric metal cylinders I and 2 which are joined at opposite ends by annular headers 3 and 4. As illustrated, the headers are provided by flanges 5 and 6 at the outer and inner edges thereof, and these flanges are bonded to the walls I and 2, as by welding to provide a hermetically sealed metal envelope. In the illustrated embodiment proviion for fluid cooling is made by additional metal cylinders l and 8 which are arranged in spaced relation with respect to the cylindrical walls I 2 Claims. (01. 250-275) and2 of the envelope. As illustrated, the cylinders l and 2 are spaced from the corresponding walls I and 2 by suitable vanes or wires 9 which dividethe fluid receiving space into spiral passages. The cooling jackets thus formed are closed at opposite ends of the device by extensions IQ of the cylinders l and land which. are welded or otherwise bonded to the ends of the envelope. The cooling passages thus provided are connected with suitable inlet and outlet conduits l I and [2.

The electrodes for the discharge device may include a pool-type cathode, such as a body of mercury I3 supported on the lower header 4. The cooperating anode I4 is supported from the upper header 3 and as illustrated is preferably in the form of an annulus of graphite or similar material. As illustrated, the anode is supported from the upper header by a plurality of studs l5 each of which is secured at one end of the anode and at the other end to a metal cap [5' which is supported from the header 3 in hermetically sealed relation with respect thereto by a cylindrical sealing member l6 formed of glass or similar insulating material. The sealing member is joined to an upstanding flange ll formed on the header 3 and surrounding an opening therein through which the stud [5 extends. It will be understood that baflie structures may be employed in the region between the anode and cathode, if desired, and that these baflles may be used as control electrodes in accordance with practices well known in the art.

In order to initiate an arc discharge within the device, I provide a starting electrode iii of the immersion ignitor type. The electrode is supported in insulated relation with respect to the envelope by means of a suitable lead-in seal l9, with the end of the electrode immersed in the liquid cathode in a, manner well understood in the art.

It will be appreciated that the cup-like members l5 provide externally accessible terminals for completing the circuit with the anode. Suitable bus-bars or studs 20 are brazed or otherwise bonded to the lower header 4 to provide external connections for the cathode. In operation of the device, it will be readily appreciated that the arc discharge takes place between the surface of the cathode l3 and the anode l4, and is initiated by passing a predetermined minimum current through the starting electrode l8. As a result of the construction of the envelope and the annular shape of the anode and cathode, both the inner and outer portions of the discharge may be cooled through the side wall of the envelope. This is scribed above. The structure is, at the:same.-.t'ime,,,

simple and readily manufactured by methods now employed in the construction of metal envelope electric discharge devices.

While I have described a particular;.embcdirrrent.-; of my invention, it will be appanent'...to-;those skilled in the art that many changes andrmodifications may be made withont departirrg my invention in its broader aspects, and I aim; therefore, to cover in the appended claims all such changes and modifications as fallfiwith'in zthertrue A spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the United States is:

I. An 'e'lectricdi'scharge deviceof the single" anode type'comprising an envelope including con centric cylindrical wall portions jointed togetherat opposite ends by annularwall--portions; -acathode comprising'a pool cf'conductingi liquid inone' 25" end of said envelope, aniannular anode supported Number within said envelope inspa'ced relation" to "said" cathode, the discharge path between said cathode and said anode having an annular cross section defined by the concentric walls of said envelope.

2. An electric discharge device of the single anode type comprising an envelope including a pair of annular headers, a pair of concentric cylindrical metal walls joined at opposite ends bysaid' headers to "provide an envelope having a substantially annular cross section, an ionizable medium Within said envelope, an annular anode supported from .one: of said headers in insulated relationixwitl'rrespect to the envelope and a cathode within said envelope in spaced relation with respect tosaid anode:

KENNETH C. DE WALT.

REFERENCES CITED The/following references are of record in the file of this patent:

UNITED STATES PATENCETS Number Name Date 2,420,829 Marshall May 20, 194? FOREIGN PATENTS Country Date 205,349 Switzerland- Sept. 1, 1939 

